I have posted this question on eng-tips too.
I found out that a lot of people are getting confused with this question and I read a lot of interesting discussions but got to no conclusion. Any help on this will be really appreciated.
I have a situation in which I have a column channel which is welded (all around) to a base plate. The base plate is bolted to the concrete slab by 4 bolts. For these type of situations, I used to consider the base as pinned and design base plate for shear/axial loads only. I know that’s not totally true as there is always some rotation restraint but that was a conservative assumption.
Recently my supervisor considered the same situation as fixed and I am really confused as to why he did that. He actually went ahead and modified the base conditions further. He considered base to be pinned in minor axis bending of the channel and fixed for major axis bending. Can someone explain to me as to how these conditions are fixed and pinned in another direction?